Cutting inserts with serrated cutting edges enable higher metal removal rates as compared with cutting inserts having non-serrated cutting edges. However, this is achieved at the expense of rougher surface finish. In order to improve the surface finish, the cutting inserts are mounted on the milling cutter with the serrations of consecutive cutting inserts offset, or out of phase, in relation to each other.
There are many examples of cutting inserts with serrated cutting edges disclosed in the art. Triangular, square, round, and rectangular shaped cutting inserts are disclosed, respectively, in U.S. Pat. No. 3,574,911; U.S. Pat. No. 3,636,602; U.S. Pat. No. 3,922,766; and U.S. Pat. No. 4,936,719.
However, all the prior art milling cutters using cutting inserts with serrated cutting edges suffer from the same problem, namely, the operative cutting teeth (i. e., “crests” of the serrations) are not supported by the milling cutter body. In other words, the operative cutting teeth project beyond the adjacent milling cutter body surface. Consequently, the operative cutting teeth are liable to break off during milling operations.
Moreover, the prior art cutting inserts with serrated cutting edges all have the form of flat slabs with opposing flat parallel rake and base surfaces. When such prior art inserts are mounted in an insert pocket, the flat base surface of the cutting insert abuts a corresponding flat support surface of the insert pocket. The cutting insert is retained in the insert pocket by means of a clamp that presses down on the rake surface of the cutting insert. Such an arrangement is not particularly robust, and twisting moments acting on the cutting insert during milling operations will tend to rotate the cutting insert from its initial position.
It is an object of the present invention to provide a milling cutter and a cutting insert therefor, the cutting insert having serrated cutting edges, that significantly overcome the aforementioned disadvantages.